You'll ideally eliminate the back-and-forth to the mechanic that comes with high-mileage cars, and you'll probably get a safer, more up-to-date, more fuel-efficient vehicle by getting something new.
Typically, owners of high-mileage vehicles still like them -- or at the very least the competitive aspect of seeing how far they can get without problems.
It's abundantly clear that the most successful high-mileage owners are those who understand the cost-effectiveness and importance of addressing the small problem before it becomes a larger one.